Joe Yabuki is a troubled youth, whose only solution to problems is throwing punches at them. What he lacks in manners and discipline, he makes up for with his self-taught fighting skills. One day, while wandering the slums of Doya, Joe gets into a fight with the local gang. Although greatly outnumbered, he effortlessly defeats them, drawing the attention of Danpei Tange—a former boxing coach turned alcoholic. Seeing his potential, he offers to train Joe into Japan's greatest boxer. At first, Joe dismisses Danpei as a hopeless drunk; but after the trainer saves his life, he agrees to live with him and learn the art of boxing. Unfortunately, Joe's personality makes him an unruly student, and he often falls back to his old ways. To survive the harsh world of his new career, Joe needs to trust his mentor and master the techniques taught to him. However, the road to becoming a professional boxer is rife with struggles that will test his mettle to the end. [Written by MAL Rewrite]

Yabuki Joe is left downhearted and hopeless after a certain tragic event. In attempt to put the past behind him, Joe leaves the gym behind and begins wandering. On his travels he comes across the likes of Wolf Kanagushi and Goromaki Gondo, men who unintentionally fan the dying embers inside him, leading him to putting his wanderings to an end. His return home puts Joe back on the path to boxing, but unknown to himself and his trainer, he now suffers deep-set issues holding him back from fighting. In attempt to quell those issues, Carlos Rivera, a world renowned boxer is invited from Venezuela to help Joe recover.

Romeo is a kindhearted and courageous boy living with his family in a small village in Switzerland. Unfortunately, Romeo becomes the interest of a man named Luini, known as "The God of Death," who is infamous for buying children and selling them as chimney sweeps in Milan. While visiting the village, Luini burns down Romeo's family cornfield in an attempt to have Romeo as his own. With the cornfield gone and his father sustaining a head injury trying to put out the fire, Romeo bravely sells himself to the God of Death in order to help his family afford a doctor. On his way to Milan, Romeo meets a boy named Alfredo Martini and they quickly become friends. Just as Alfredo is sold to a different master, the two boys swear eternal friendship and vow to meet again. As a chimney sweep, Romeo faces many hardships and abuse, especially from his master's family and a gang known as the Wolf Pack. But after reuniting with Alfredo, the two form a fraternity of chimney sweeps called "The Black Brothers," who will learn to fight against the Wolf Pack and help each other in times of need. [Written by MAL Rewrite]

When Subaru Natsuki leaves the convenience store, the last thing he expects is to be wrenched from his everyday life and dropped into a fantasy world. Things aren't looking good for the bewildered teenager; however, not long after his arrival, he is attacked by some thugs. Armed with only a bag of groceries and a now useless cell phone, he is quickly beaten to a pulp. Fortunately, a mysterious beauty named Satella, in hot pursuit after the one who stole her insignia, happens upon Subaru and saves him. In order to thank the honest and kindhearted girl, Subaru offers to help in her search, and later that night, he even finds the whereabouts of that which she seeks. But unbeknownst to them, a much darker force stalks the pair from the shadows, and just minutes after locating the insignia, Subaru and Satella are brutally murdered. However, Subaru immediately reawakens to a familiar scene—confronted by the same group of thugs, meeting Satella all over again—the enigma deepens as history inexplicably repeats itself. [Written by MAL Rewrite]